Bronchial Asthma

DefinitionEpidemiologyRisk factors Pathology & pathogenesisDiagnosisManagement

DefinitionA chronic inflammatory disorder of the airways associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing. These episodes are usually associated with reversible airway obstruction.

EpidemiologyAsthma is a problem worldwide, with an estimated 300 million affected individualsPrevalence increasing in many countries, especially in childrenA cause of a significant number of preventable deathsA major cause of school/work absence

Asthma Prevalence and MortalitySource: Masoli M et al. Allergy 2004

Factors Influencing the Development and Expression of AsthmaHost factorsGeneticObesity Sex

Cont. Risk FactorsEnvironmental FactorsAllergens (Indoor and Outdoor)Infections (RCV and Parainfluenza)Hygiene hypothesisOccupational sensitizersTobacco smokingAir pollutionDiet (breast feeding, antioxidants, n-6 PUFA, 3-n PUFA)

Pathology & Pathogenesis

Source: Peter J. Barnes, MDAsthma Inflammation: Cells and Mediators

Source: Peter J. Barnes, MDAsthma Inflammation: Cells and Mediators

Mechanisms: Asthma Inflammation

DiagnosisHistory and physical examinationPulmonary function testsOther laboratory tests

Questions to Consider in the Diagnosis of AsthmaRecurrent attacks of wheezing?Troublesome cough at night?Wheeze or cough after exercise?Wheeze or tightness after exposure to allergens or pollutants?Does the cold go to the chest or take more than 10 days to clear?Are symptoms improved by asthma treatment?

Pulmonary Function TestsSpirometryPeak expiratory flow rateAirway responsiveness

Pulmonary Function TestsSpirometry: improvement in FEV1 after bronchodilator by 12% (or >200ml)PEFRimprovement by 60ml (or 20%)or diurnal variation of > 20%Airway responsivenesshistamine, methacholine, exercise

1Time (sec)2345FEV1VolumeNormal SubjectAsthmatic (After Bronchodilator)Asthmatic (Before Bronchodilator)Note: Each FEV1 curve represents the highest of three repeat measurementsTypical Spirometric (FEV1) Tracings

Measuring Airway Responsiveness

Laboratory TestsChest X-rayBlood testsEosinophil countIgE levelSkin tests

Management of AsthmaEducation and develop patient/doctor partnershipIdentify and reduce exposure to risk factorsPharmacotherapy of asthmaAssess, treat, and monitor asthma

Pharmacotherapy of Asthma

ControllersInhaled glucocorticoidLong-acting inhaled b2-agonistsLeukotriene modifiersTheophyllineCromonesAnti-IgESystemic glucocorticoids

Comparative Daily Dosages of ICS (mg)

RelieversRapid- acting b2-agonistsAnticholinergicsSystemic glucocorticoidsTheophylline

Factors Affecting ComplianceRoute of drug administration (oral vs inhaled)Complexity of drug regimenSide effects of medicationsSupport of family and health care professionals

Treatment GoalsAchieve and maintain control of symptomsMaintain normal activity levels, including exerciseMaintain pulmonary function as close to normal as possiblePrevent asthma exacerbationsAvoid adverse effects from asthma medicationsPrevent asthma mortality

What is Controlled Asthma? Day time symptoms: non or twice /weekNo limitations of activityNo nocturnal symptomsNeed for reliever : non or twice/week Normal lung functionNo exacerbations

Classification of Asthma Severity

Levels of Asthma Control

CharacteristicControlled(All of the following)Partly controlled (Any present in any week)Uncontrolled Daytime symptomsNone (2 or less / week)More than twice / week3 or more features of partly controlled asthma present in any week

Limitations of activitiesNoneAnyNocturnal symptoms / awakeningNoneAnyNeed for rescue / reliever treatmentNone (2 or less / week)More than twice / weekLung function (PEF or FEV1)Normal< 80% predicted or personal best (if known) on any dayExacerbationNone One or more / year 1 in any week

Stepping Down TreatmentReview medications after 3-6 months of stability and if stable reduce medications by 25-50%

Features of Acute Severe AsthmaPEFR 33- 50% ( 25/minPulse rate > 110/minPulsus paradoxusUse of accessory muscles of breathing

Features of Life Threatening AsthmaRisk factor for near fatal asthmaPEFR < 33% (

Management of Acute ExacerbationsPEF 50-75% Uncontrolled asthmaOxygen saturationNebulized b-2 agonistCheck PEF >75% Home 50-75% Home with short course of prednisolone

Management of Acute ExacerbationsPEF < 50% Acute severe asthmaOxygenNebulized b-2 agonistNebulized ipratropiumCheck PEF > 50% Home < 50% Admit Systemic steroids

Management of Acute ExacerbationsPEF< 33% Life threatening asthmaAdmit to ICUOxygenNebulized b-2 agonist and ipratropiumSystemic steroidsConsider assisted ventilation

When to Discharge Patient Home ?24 hours on home medicationsOral prednisoloneInhaled corticosteroidsInhaled long acting b-2 agonistInhaled short acting b-2 agonistEarly appointment with clinic (2 weeks)PEF > 75% of predicted or personal bestPEF variability < 20%